A better understanding of soft tissue stress and its role in supporting the medial longitudinal arch in flexible flatfoot could help to guide the clinical treatment. In this study, a 3-Dimensional finite element (FE) foot model was reconstructed to measure the stress of the soft tissue, and its variation in different scenarios related to flexible flatfoot. All bones, cartilages, ligaments and related tendons around the ankle, and fat pad were included in the finite element model. The equivalent stress on the articular surface of the joints in the medial longitudinal arch and the maximum principal stress of the ligaments around the ankle were obtained. The results show that the plantar fascia (PF) is the main tissue in maintaining the medial longitudinal arch. The equivalent stress of all the joints in the medial longitudinal arch increases when the PF attenuation and the talonavicular joint increases, while other joints decreases when all the three tissue attenuation. Moreover, the maximum principal stress variation of calcaneofibular ligament is largest when the PF attenuation and the tibionavicular ligament and posterior tibiotalar ligament are largest when the posterior tibial tendon (PTT) attenuation. The maximum principal stress variation of tibionavicular ligament and posterior tibiotalar ligament are even larger when all the three tissue attenuation. These findings support that the PF is the main factor in maintaining the medial longitudinal arch. The medial longitudinal arch collapse mainly affects the talonavicular joint and the calcaneofibular ligament, the tibionavicular ligament and the posterior tibiotalar ligament. This approach could help to improve the understanding of adult-acquired flatfoot deformity (AAFD).

中文翻译：

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与柔性扁平足畸形相关的主要软组织应力分析：有限元研究。

更好地了解软组织应力及其在支持扁平足内侧纵弓中的作用有助于指导临床治疗。在这项研究中，重建了一个 3 维有限元 (FE) 足部模型来测量软组织的应力，以及它在与柔性扁平足相关的不同情况下的变化。踝关节周围的所有骨骼、软骨、韧带和相关肌腱以及脂肪垫都包含在有限元模型中。求出内侧纵弓关节面的等效应力和踝关节周围韧带的最大主应力。结果表明，足底筋膜（PF）是维持内侧纵弓的主要组织。当PF衰减和距舟关节增加时，内侧纵弓所有关节的等效应力均增加，而当三种组织均衰减时，其他关节的等效应力减小。此外，PF衰减时跟腓韧带的最大主应力变化最大，胫后肌腱（PTT）衰减时胫舟韧带和胫距后韧带最大。当三种组织均衰减时，胫舟韧带和胫距后韧带的最大主应力变化更大。这些发现支持PF是维持内侧纵弓的主要因素。内侧纵弓塌陷主要影响距舟关节和跟腓韧带，胫舟韧带和胫距后韧带。这种方法有助于提高对成人获得性扁平足畸形 (AAFD) 的理解。